In the manufacture of hollow plastic containers it is common to form a parison into a neck portion and a body portion, and to blow the body portion outwardly to form the container. It is also common to thereafter complete the container by removing material from the internal diameter of the neck and the top portion. In order to provide such designs, it is sometimes necessary to have a high blow ratio, that is the ratio of the diameter of the body portion divided by the diameter of the neck portion.
In such prior methods, in order to reduce the blow ratio, it has become necessary to mold the container with flashing outside of the neck portion. This necessitates a subsequent operation for removing the side flash, as well as the operation of reaming or cutting the inside diameter of the finish. An alternative is to make the bottle without flashing outside of the neck by having a high blow ratio. This causes high incidence of rejections due to poor bottle sidewall uniformity and still requires cutting the inside diameter of the finish.
Among the objectives of the present invention are to provide a novel method and resultant article which reduce the blow ratio; which method also avoids cutting through barrier materials in the case of a plastic container with an internal barrier layer; and which avoids the necessity for removal of side flash.
In accordance with the invention, a hollow plastic container is provided having a finish which has a diameter less than the diameter of the body of the final container. The container is made by forming a parison with a neck portion for defining the finish and a body portion, and thereafter expanding the body portion to a cross section greater than the cross section of the neck portion. The neck is then trimmed by removing plastic material from the outside of the neck and from the top of the neck to form the finish to the final dimensions. In one form, the parison is a multi-layer parison in order to form a multi-layer plastic container.